* {
  box-sizing: border-box;
  padding: 0;
  margin: 0;
}
html,
body,
#app {
  height: 100%;
}
.w {
  width: 1200px;
  margin: 0 auto;
}
.clearfix {
  zoom: 1;
}
.clearfix::after,
.clearfix::before {
  content: '';
  display: table;
  clear: both;
  height: 0;
  visibility: hidden;
}
img {
  vertical-align: middle;
}
a {
  text-decoration: none;
}
li {
  list-style: none;
}
